Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server

David Williams wrote: > Imagine 1 page with 2 rows one it. > > 1. Page level locking > > User A updates row 1 > At the same time user B updates row 2. User B has to wait for > User B to commit. You're forgetting latency. There's no way that you'd ever get immediate concurrency as in your second scenario below. > 2. With row level locking > User A updates row 1 > User B updates row 2 (with no waiting). > > How can 1 be faster than 2 if user B has to wait? The wait would be negligible. In scenario 2 you also have a wait (its hidden unless you think about it so you won't see it). It goes like this, a database server services request 1 then it services the next request (in this case 2). The wait is implicit. So you don't really gain anything. > > For a finely tuned application, row level locking > > does *not* matter. > Lock granularity is still a problem. Why do UNIX kernels lock > individual files and data structures rather than having one large > kernel lock? Try reading Hey but they don't lock rows of text in a file do they? -am